(1) Field of the Invention
The present invention relates to an energy dissipation device for a car body of a multielement vehicle, in particular a rail vehicle, the energy dissipation device having a damping unit having a regeneratively implemented damping element for damping traction and impact forces occurring in normal travel operation, as well as an energy dissipation unit having a destructively implemented energy dissipation element, the destructively implemented energy dissipation element being designed to respond after a previously established critical impact force is exceeded and to convert at least a part of the impact forces transmitted via the energy dissipation device into heat and deformation work by plastic deformation and thus dissipate them.
(2) Description of Related Art
Energy dissipation devices of the type cited at the beginning are generally known in principle from the prior art and are used, for example, in rail vehicle technology in particular as a shock absorber. Such a shock absorber typically comprises a combination of a damping unit (for example, in the form of a spring apparatus) and an energy dissipation unit. The damping unit is used for damping the traction and impact forces occurring in normal travel operation, while the vehicle is protected in particular even at greater collision speeds using the energy dissipation unit.
Typically, the damping unit absorbs traction and impact forces up to a defined dimension and relays forces exceeding this dimension into the vehicle chassis. Traction and impact forces which occur, for example, between the individual car bodies during normal travel operation in a multielement rail vehicle are thus absorbed in this shock absorber, which is typically implemented as regenerative.
If the operating load of the damping unit, which is typically implemented as regenerative, is exceeded, in contrast, upon impact of the vehicle on an obstruction or upon abrupt braking of the vehicle, for example, the danger arises that the damping unit and the possibly provided joint or coupling connection between the individual car bodies and/or more generally expressed the interface between the individual car bodies will possibly be destroyed or damaged. In any case, the damping unit is not sufficient for damping the total incident energy. The damping unit is thus no longer incorporated in the energy dissipation concept of the overall vehicle.
To prevent the incident impact energy from being transmitted directly to the vehicle chassis in such a crash case, connecting an energy dissipation unit downstream from the damping unit is known from rail vehicle technology. The energy dissipation unit typically responds after the operating load of the damping unit is exceeded and is used to at least partially dissipate the incident impact energy, i.e., convert it into heat energy and deformation work, for example. Providing an energy dissipation unit of this type is fundamentally advisable for reasons of derailing safety, to prevent the impact energy incident in case of a crash from being transmitted directly to the vehicle chassis, and in particular the vehicle chassis from being subjected to extreme loads and being damaged or even destroyed in certain circumstances.
To protect the vehicle chassis from damaged upon strong collision impacts, an energy dissipation unit having a destructively implemented energy dissipation element is frequently used as a so-called “shock absorber”, which is designed in such a way, for example, that it responds after the operating dissipation of the damping unit is exhausted and at least partially absorbs and dissipates the energy transmitted by the force flux via the energy dissipation element. A deformation pipe comes into consideration in particular as the energy dissipation element, in which, after a critical impact force is exceeded, the impact energy introduced into the energy dissipation unit is converted into deformation work and heat by an (intended) plastic deformation in a destructive way.
An automatic middle buffer coupling 100 for a rail vehicle known from the prior art is shown FIG. 1, this middle buffer coupling 100 being provided with an energy dissipation device of the type cited at the beginning. The middle buffer coupling 100 is linked via a bearing bracket 103 to the front face of a car body (not explicitly shown) in such a way that horizontal and vertical pivoting and axial rotation (cardanic movement) of the coupling rods 101 with the coupling head 102 are made possible.
In the middle buffer coupling 100 shown in FIG. 1, a damping unit 110 is implemented in the form of a traction/impact unit, which absorbs traction and pressure forces up to a defined size and relays forces exceeding this undamped into the vehicle chassis (not explicitly shown) of the car body via the bearing bracket. Various variants come into consideration as the traction/impact unit 110. In the embodiment shown in FIG. 1, a friction spring integrated in the coupling rod 101 on one hand and a spheroplastic bearing on the other hand are used as the traction/impact unit. Using this measure it is possible that the traction/impact forces occurring in normal travel operation and transmitted from the coupling head 102 via the coupling rod 101 to the bearing bracket 103 are damped in the damping unit 110 (traction/impact unit and/or spring apparatus) integrated in the coupling rod 101.
To protect the vehicle chassis (not explicitly shown in FIG. 1) at greater collision velocities, the damping unit 110 (traction/impact unit and/or spring apparatus) integrated in the coupling rod 101 has an energy dissipation unit 120 connected downstream, which is used as a shock absorber. The energy dissipation unit 120 has a destructively implemented energy dissipation element 121 in the form of a deformation pipe. The deformation pipe 121 is designed to respond after the operating load of the damping unit 110 is exceeded and to at least partially dissipate the impact energy introduced into the energy dissipation unit 120 after the operating dissipation of the damping unit 110 is exhausted.
The dissipation of the impact energy occurs in multiple stages. After the operating load of the damping unit 110 is exceeded, the coupling rod 101 and the bearing bracket 103 are shifted in relation to the car body in the direction of the car body. As already noted, the energy dissipation element 121 is implemented as a deformation pipe. The deformation pipe 121 has its end on the car body side projecting into a conical hole provided in a nozzle plate—although this is not explicitly shown in FIG. 1. In case of a crash, i.e., after exceeding the operating load of the damping unit 110, the bearing bracket 103 shifts with the deformation pipe 121 in relation to the chassis of the rail vehicle in the direction of the nozzle plate, the deformation pipe 121 being pressed through the conical hole provided in the nozzle plate with reduction of its cross-section and converting at least a part of the total incident impact energy into heat energy and plastic deformation work.
Accordingly, the energy dissipation device used in the middle buffer coupling 100 shown in FIG. 1 comprises the damping unit 110 integrated in the coupling rod 101 on one hand and the energy dissipation unit 120 connected downstream from the damping unit 110 on the other hand. This combination of damping unit 110 and downstream energy dissipation unit 120 not only allows damping of the traction and impact forces occurring in normal travel operation, but rather also offers protection from damage to the vehicle chassis in the event of strong collision impacts.
The disadvantage of this energy dissipation device known from the prior art may be seen in that—because of the combination of damping unit and downstream energy dissipation unit used—a relatively large installation space must be available to implement the energy dissipation device as a whole. On one hand, it is necessary to integrate the damping unit in the coupling rod, as a result of which the coupling rod may not be shortened arbitrarily, but rather must fundamentally have a specific minimal length. On the other hand, because of the energy dissipation unit connected downstream from the damping unit, an installation space is also additionally to be provided behind the front face of the car body.
This installation space to be provided for implementing the energy dissipation device may not be provided in all vehicle and/or car body types, however, because the front face design of the car body only offers restricted installation space, for example.